This invention relates to novel imidazole compounds having pharmacological activity, to a process for their production and to a pharmaceutical composition containing the same.
Adenosine (Ado) is an endogenous purine nucleoside released by cells as part of the normal metabolic machinery. Ado has wide variety of biological activities, namely potent antiinflammatory and immunosuppressive properties, protective effects in cardiovascular and cerebrovascular ischemia, anticonvulsant effects and modulation effects of platelet aggregation, lipolysis, glycogenesis, blood flow and neurotransmission. Ado shows the biological activities by binding to its receptors anchored in the cell membrane. Therefore, it is the beneficial treatment for many diseases to perform the pharmacological elevation of extracellular Ado concentrations.
Adenosine deaminase (ADA) catalyzes an essentially irreversible deamination of adenosine or deoxyadenosine to inosine or deoxyinosine, respectively. In the last 10 years, ADA, which was considered to be cytosolic, has been found on the cell surface of many cells. Thus, blocking ADA activity with specific inhibitor is the potent way to elevate Ado concentrations in biological systems and the beneficial treatment for many diseases.
Some compounds have known to have inhibitory activity of ADA (J. Med. Chem. 27, 274-278, 1984; ibid. 31, 390-393, 1988; ibid. 34, 1187-1192, 1991; ibid. 35, 4180-4184, 1992; ibid. 37, 305-308, 1994; ibid. 37, 3844-3849, 1994; and WO98/02166).
Known imidazole compounds with pharmaceutical activity other than ADA inhibitory activity are described in U.S. Pat. No. 4,451,478 and WO97/26883.
Furthermore, some imidazole derivatives having ADA inhibitory activity have been reported, for example, as described in Drug Developement Research 28, 253-258, 1993.
This invention relates to novel imidazole compounds, which have pharmaceutical activity such as ADA inhibiting activity, to a process for their production, to a pharmaceutical composition containing the same and to a use thereof.
One object of this invention is to provide the novel imidazole compounds, which have an ADA inhibiting activity.
Another object of this invention is to provide a process for production of the imidazole compounds.
A further object of this invention is to provide a pharmaceutical composition containing the imidazole compound as an active ingredient.
Still further object of this invention is to provide a use of the imidazole compound for manufacturing a medicament for treating or preventing various diseases, or a method of treating or preventing various diseases by administering the imidazole compound in an effective amount to elevate adenosine concentration.
The imidazole compounds of this invention can be represented by the following formula (I): 
wherein R1 is hydrogen, hydroxy, protected hydroxy, or aryl optionally substituted with suitable substituent(s);
R2 is hydrogen or lower alkyl;
R3 is hydroxy or protected hydroxy;
R4 is cyano, (hydroxy)iminoamino(lower)alkyl, carboxy, protected carboxy, heterocyclic group optionally substituted with amino, or carbamoyl optionally substituted with suitable substituent(s); and
xe2x80x94Axe2x80x94 is xe2x80x94Qxe2x80x94 or xe2x80x94Oxe2x80x94Qxe2x80x94, wherein Q is single bond or lower alkylene, provided that when R2 is lower alkyl, then R1 is hydroxy, protected hydroxy, or aryl optionally substituted with suitable substituent(s), its prodrug, or their salt.
The compound (I), its prodrug, or their salt can be prepared by the following processes. In the following formulae, compounds may be prodrugs or their salts. 
wherein R1, R2, R3, R4, and A re each as defined above, and X is hydroxy or a leaving group, provided that R3 is not hydroxy.
In this process the compound (I) can be produced by reacting the compound (IV), where X is hydroxy, with alkanesulfonyl chloride (i.e., methanesulfonyl chloride, etc.) or arylsulfonyl chloride (i.e., toluenesulfonyl chloride, etc.) in the presence of a base such as triethylamine or pyridine in a solvent such as dichloromethane, chloroform, tetrahydrofuran, or diethyl ether from 0xc2x0 C. to room temperature for about 1 hour and reacting the resulting sulfonate with the compound (III) in the presence of a base such as sodium hydride, potassium tert-butoxide, or potassium carbonate in a solvent such as dimethylformamide (DMF) from room temperature to 100xc2x0 C. for 5 to 100 hours. Alternatively, the compound (III) can be reacted with the compound (IV) in the presence of a base such as sodium methoxide, potassium tert-butoxide, or sodium hydride to give the compound (I).
The compound (I) wherein R3 is hydroxy can be obtained by the following process: 
In the reaction formula R1 and R4 are as defined above and Rxe2x80x2 is a hydroxy protective group.
In process 2, the compound (I-1) can be produced by reducing the compound (II) using a reducing agent such as sodium borohydride in a solvent such as methanol, ethanol, tetrahydrofuran, or water at 0xc2x0 C. to reflux temperature for 30 minutes to 72 hours.
When the compound (I) contains a protected hydroxy group, the protected hydroxy group can be converted to a hydroxy group by a known method, for example, by reacting the compound with a deprotecting agent such as palladium hydroxide on carbon/cyclohexane, iodotrimethylsilane or tetrabutylammonium fluoride in a solvent such as ethanol, chloroform or tetrahydrofuran.
The compound (I) where R4 is (hydroxy)iminoamino(lower)alkyl, heterocyclic group or substituted carbamoyl can be prepared from the compound (I) where R4 is cyano or protected carboxy by reacting the latter with the compound corresponding to R4 of the former with or without a condensing agent such as sodium methoxide at room temperature to 120xc2x0 C. for 2 to 72 hours.
The starting compound (II) can be prepared by the following reaction. 
In the reaction formula R1, R4, Rxe2x80x2, and A are as defined above.
This reaction can be performed in the same manner as in Process 1.
In the following, suitable examples of the definitions to be included within the scope of the invention are explained in detail.
The term xe2x80x9clowerxe2x80x9d means a group having 1 to 6 carbon atom(s), unless otherwise provided.
Suitable xe2x80x9clower alkylxe2x80x9d and lower alkyl moiety of xe2x80x9clower alkoxyxe2x80x9d include a straight or branched one such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, hexyl, or the like, with methyl being preferred.
Suitable xe2x80x9clower alkylenexe2x80x9d may be straight or branched one having 1 to 8. carbon atom(s), such as methylene, ethylene, trimethylene, tetramethylene, pentametylene, hexamethylene, or the like.
Suitable xe2x80x9cprotected hydroxyxe2x80x9d includes lower alkoxy optionally substituted with aryl; acyloxy; or tri(lower)alkylsilyloxy (i.e., trimethylsilyloxy, tert-butyldimethylsilyloxy, etc.); or the like.
Suitable hydroxy protective groups in the protected hydroxy group include lower alkyl optionally substituted with aryl; acyloxy; tri(lower)alkylsilyloxy (i.e., trimethylsilyloxy, tert-butyldimethylsilyloxy, etc.); or the like.
Suitable xe2x80x9chalogenxe2x80x9d includes fluorine, chlorine, bromine, or iodine.
Suitable xe2x80x9carylxe2x80x9d and aryl moeity of xe2x80x9caroylxe2x80x9d include phenyl, naphthyl, tolyl, xylyl, or the like, with phenyl and naphthyl being preferred.
Suitable xe2x80x9cprotected carboxyxe2x80x9d includes lower alkoxycarbonyl (e.g., methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, butoxycarbonyl, 2,2,2-trichloroethoxycarbonyl, etc.), aryloxy-carbonyl (e.g., phenoxycarbonyl, 4-nitrophenoxycarbonyl, etc.), ar(lower)alkoxycarbonyl (e.g. benzyloxycarbonyl, 4-nitrobenzyloxycarbonyl, etc.), or the like.
Suitable carboxy protective groups in the protected carboxy group include lower alkyl (e.g., methyl, ethyl, or tert-butyl), halo(lower)alkyl (e.g., 2-iodomethyl or 2,2,2-trichloroethyl), ar(lower)alkyl (e.g., benzyl, trityl, 4-methoxybenzyl, 4-nitrobenzyl, phenethyl, bis(methoxyphenyl)methyl, 3,4-dimethoxybenzyl or 4-hydroxy-3,5-di-tert-butylbenzyl), aryl (e.g., phenyl, naphthyl, tolyl, or xylyl), and the like. More suitable examples are lower alkyl such as methyl, ethyl, or tert-butyl, and ar(lower)alkyl such as benzyl.
Suitable xe2x80x9cacylxe2x80x9d and acyl moiety of xe2x80x9cacyloxyxe2x80x9d include lower alkanoyl, aroyl, or the like.
Suitable xe2x80x9clower alkanoylxe2x80x9d includes formyl, acetyl, propionyl, butyryl, isobutyryl, valeryl, isovaleryl, pivaloyl, hexanoyl, or the like.
Suitable xe2x80x9caroylxe2x80x9d may be benzoyl, naphthoyl, toluoyl, xyloyl, or the like.
In the definition, unless stated otherwise, xe2x80x9clower alkanoylxe2x80x9d and xe2x80x9caroylxe2x80x9d may be substituted with one or more substituent(s) selected from halogen, cyano, nitro, lower alkyl, and a combination thereof.
Suitable xe2x80x9cacyloxyxe2x80x9d includes acetyloxy, trifluoroacetyloxy, or the like.
Suitable xe2x80x9cleaving groupxe2x80x9d may be halogen, acyloxy (e.g., acetyloxy, trifluoroacetyloxy, etc.), lower alkylsulfonyloxy (e.g., methanesulfonyloxy, etc.), triarylphosphinoxy (e.g., xe2x80x94Oxe2x80x94P+(C6H5)3, etc.), or the like.
Suitable xe2x80x9csubstituent(s)xe2x80x9d of xe2x80x9ccarbamoylxe2x80x9d include amino, hydroxy, lower alkyl, lower alkylsulfonyl, and aminoimino(lower)alkyl optionally substituted with hydroxy, or the like.
Suitable xe2x80x9csubstituent(s)xe2x80x9d of xe2x80x9carylxe2x80x9d include lower alkyl optionally substituted with hydroxy or protected carboxy; lower alkoxy optionally substituted with aryl; hydroxy; amino; acyl; halogen; carboxy; protected carboxy; carbamoyl; lower alkylenedioxy, or the like.
Suitable xe2x80x9cheterocyclic groupxe2x80x9d contains at least one hetero atom selected from nitrogen, sulfur, and oxygen atom and may be saturated or unsaturated, monocyclic or polycyclic heterocyclic group. Preferable examples of the heterocyclic group include N-containing heterocycyclic group described below.
(1) unsaturated 3 to 7-membered, preferably 5- or 6-membered heteromonocyclic group containing I to 4 nitrogen atoms, for example, pyrrolyl, pyrrolinyl, imidazolyl, pyrazolyl, pyridyl, pyrimidinyl, pyrazinyl, pyridazinyl, triazolyl (e.g., 4H-1,2,4-triazolyl, 1H-1,2,3-triazolyl, 2H-1,2,3-triazolyl, etc.), tetrazolyl (e.g., 1H-tetrazolyl, 2H-tetrazolyl, etc.), etc.;
(2) saturated 3 to 7-membered, preferably 5- or 6-membered heteromonocyclic group containing 1 to 4 nitrogen atoms (e.g., pyrrolidinyl, imidazolidinyl, piperidyl, piperazinyl, etc.);
(3) unsaturated 3 to 7-membered, preferably 5- or 6-membered heteromonocyclic group containing 1 to 2 oxygen atoms and 1 to 3 nitrogen atoms, for example, oxazolyl, isoxazolyl, oxadiazolyl (e.g., 1,2,4-oxadiazolyl, 1,2,4-oxadiazolinyl, 1,3,4-oxadiazolyl, 1,2,5-oxadiazolyl, etc.), etc.;
(4) saturated 3 to 7-membered, preferably 5- or 6-membered heteromonocyclic group containing 1 to 2 oxygen atoms and 1 to 3 nitrogen atoms (e.g., morpholinyl, etc.);
(5) unsaturated 3 to 7-membered, preferably 5- or 6-membered heteromonocyclic group containing 1 to 2 sulfur atoms and 1 to 3 nitrogen atoms, for example, thiazolyl, thiadiazolyl (e.g., 1,2,4-thiadiazolyl, 1,3,4-thiadiazolyl, 1,2,5-thiadiazolyl, etc.), etc.;
(6) saturated 3 to 7-membered preferably 5- or 6-membered heteromonocyclic group containing 1 to 2 sulfur atoms and 1 to 3 nitrogen atoms (e.g., thiomorpholinyl, thiazolidinyl, etc.) and the like.
Among the above, more preferable heterocyclic group included in R4 is above-mentioned (1), in which the most preferable one is triazolyl or tetrazolyl.
Suitable salts of the compounds of the present invention are pharmaceutically acceptable conventional non-toxic salts and can be an organic acid addition salt (e.g. formate, acetate, trifluoroacetate, maleate, tartarate, oxalate, methanesulfonate, benzenesulfonate, toluenesulfonate, etc.), an inorganic acid addition salt (e.g. hydrochloride, hydrobromide, sulfate, phosphate, etc.), a salt with an amino acid (e.g. aspartic acid salt, glutamic acid salt, etc.), or the like.
The xe2x80x9cprodrugxe2x80x9d means the derivatives of compounds of the present invention having a chemically or metabolically degradable group, which becomes pharmaceutically active after biotransformation.
The compounds of formula (I) may contain one or more asymmetric centers and thus they can exist as enantiomers or diastereoisomers. Furthermore certain compounds of formula (I) which contain alkenyl groups may exist as cis- or trans-isomers. In each instance, the invention includes both mixtures and separate individual isomers.
The compounds of the formula (I) may also exist in tautomeric forms and the invention includes both mixtures and separate individual tautomers.
The compound of the formula (I) and its salt can be in a form of a solvate, which is included within the scope of the present invention. The solvate preferably include a hydrate and an ethanolate.
Also included in the scope of invention are radiolabelled derivatives of compounds of formula (I) which are suitable for biological studies.
The compound of the present invention can be purified by any conventional purification methods employed for purifying organic compounds, such as recrystallization, column chromatography, thin-layer chromatography, high-performance liquid chromatography and the like. The compounds can be identified by conventional methods such as NMR spectrography, mass spectrography, IR spectrography, elemental analysis, and measurement of melting point.
The compound (I), its prodrug, or their salt can be administered alone or in the form of a mixture, preferably, with a pharmaceutical vehicle or carrier.
The active ingredient of this invention can be used in the form of a pharmaceutical preparation, for example, in solid, semisolid or liquid form, which contains a compound (I), as an active ingredient, in admixture with an organic or inorganic carrier or excipient suitable for external (topical), enteral, intravenous, intramuscular, parenteral or intramucous applications. The active ingredient can be formulated, for example, with the conventional non-toxic, pharmaceutically acceptable carriers for ointment, cream, plaster, tablets, pellets, capsules, suppositories, solution (saline, for example), emulsion, suspension (olive oil, for example), aerosols, pills, powders, syrups, injections, troches, cataplasms, aromatic waters, lotions, buccal tablets, sublingual tablets, nasal drops and any other form suitable for use. The carriers which can be used are water, wax, glucose, lactose, gum acacia, gelatin, mannitol, starch paster, magnesium trisilicate, talc, corn starch, keratin, paraffin, colloidal silica, potato starch, urea and other carriers suitable for use in manufacturing preparations, in solid, semisolid, or liquid form, and in addition auxiliary, stabilizing, thickening and coloring agents and perfumes may be used. The active compound is included in a pharmaceutical composition in an effective amount sufficient to produce the desired effect upon the process or condition of the diseases.
The active ingredient can be formulated into, for example, preparations for oral application, preparations for injection, preparations for external application, preparations for inhalation, preparations for application to mucous membranes.
Mammals which may be treated by the present invention include livestock mammals such as cows, horses, etc., domestic animals such as dogs, cats, rats, etc. and humans, preferably humans.
While the dosage of therapeutically effective amount of the compound (I) will vary depending upon the age and condition of each individual patient, an average single dose to a human patient of about 0.01 mg, 0.1 mg, 1 mg, 10 mg, 50 mg, 100 mg, 250 mg, 500 mg, and 1000 mg of the compound (I) may be effective for treating the above-mentioned diseases. In general, amounts between 0.01 mg/body and about 1,000 mg/body may be administered per day.
The compound (I) or its pharmaceutically acceptable salts of this invention possesses ADA inhibiting activity and are thus useful in immunomodulation, especially immunosuppression, antiinflammation and treatment and prevention of various diseases for which Ado is effective. Examples of the diseases are as follows:
a) Autoimmune diseases and inflammatory conditions, e.g., various pains collagen diseases, autoimmune diseases, various immunity diseases, and the like in human beings or animals, and more particularly for the treating and/or preventing inflammation and pain in joint and muscle (e.g. rheumatoid arthritis, rheumatoid spondylitis, osteoarthritis, gouty arthritis, etc.), inflammatory skin condition (e.g. sunburn, eczema, etc.), inflammatory eye condition (e.g. conjunctivitis, etc.), lung disorder in which inflammation is involved (e.g. asthma, bronchitis, pigeon fancier""s disease, farmer""s lung, etc.), condition of the gastrointestinal tract associated with inflammation (e.g. aphthous ulcer, Crohn""s disease, atrophic gastritis, ulcerative colitis, coeliac disease, regional ileitis, irritable bowel syndrome, etc.), gingivitis, (inflammation, pain and tumescence after operation or injury), pyrexia, pain and other conditions associated with inflammation, systemic lupus erythematosus, scleroderma, polymyositis, polychondritis, periarteritis nodosa, ankylosing spondylitis, inflammatory chronic renal condition (e.g. nephrotic syndrome, glomerulonephritis, membranous nephritis, etc.), acute nephritis, rheumatic fever, Sjogren""s syndrome, Behcet disease, thyroiditis, type I diabetes, dermatomyositis, chronic active hepatitis, acute hepatitis, myasthenia gravis, idiopathic sprue, Grave""s disease, multiple sclerosis, primary billiary cirrhoris, Reiter""s syndrome, autoimmune hematological disorders (e.g. hemolytic anemia, pure red cell anemia, idiopathic thrombocytopenia; aplastic anemia, etc.), myasthenia gravis, uveitis, contact dermatitis, psoriasis, Kawasaki disease, sarcoidosis, Wegner""s granulomatosis, Hodgkin""s disease, or the like;
b) Organ or tissue allo-or xeno-transplant rejection, e.g., kidney, liver, heart, lung, combined heart-lung, bone marrow, islet cells, pancreatic, skin, chromaffin or dopamine producing cells, small bowel, or corneal transplantation. Treating and/or preventing graft-versus-host disease, such as occurs following bone marrow transplantation;
c) Various leukemias, including virus induced, or various induced lymphomas; and
d) Diseases that arise from, or are aggravated by, insufficient blood flow through a particular organ or portion thereof, e.g., heart attacks or strokes, the microvascular disease of diabetes mellitus, atherosclerosis, or events resulting in a less prolonged loss of blood flow (e.g., angina pectoris, transient ischemic attacks, bowel ischemia, kidney ischemia, intermittant claudication of skeletal muscle, migraine headaches, Raynaud""s phenomenon), or the like.
Any patents, patent applications, and publications cited herein are incorporated by reference.
In order to illustrate the usefulness of the object compound (I), the pharmacological test data of the compound (I) are shown in the following.
Adenosine Deaminase (ADA) Enzyme Assay
Test Compound
Test Method
The reaction velocity (V) is measured by a change in absorbance at 265 nm (A265) resulting from the deamination of adenosine. Human ADA was expressed and purified from ADA-deficient bacterial strain. Reaction mixtures in a total volume of 200 xcexcl contained 25 mU/ml of ADA and varying concentrations of adenosine and test compounds in 10 mM phosphate buffer saline (pH 7.4). The reaction was started by addition of ADA to a mixture of adenosine and test compound. The reaction was followed at room temperature by recording decrease in A265 for 5 minutes in SPECTRAmax 250 (Molecular Devices, USA) to automatically calculate Vmax. The inhibition constant (Ki) values of test compounds were determined by Dixon plot.
Results
Test Compound: Ki=5.9 xcexcM
Test Compound
Test Method
BALB/c mice (male, 7 weeks old) were injected i.v. with 0.1 mg/kg of lipopolysaccharides (LPS) in a total volume of 0.2 ml saline. Heparinized blood samples were taken one hour after LPS injection and plasma was collected by centrifugation. TNF-xcex1 (inflammatory cytokine) and IL-10 (anti-inflammatory cytokine) amounts in plasma were assayed by ELISA. Test compounds were administered 30 minutes before LPS injection.
Results